Naruto might be initially confused. He trusts Tsunade, so being kidnapped by her would be completely unexpected. He would probably start by asking her why she's doing this.
If Luke were kidnapped, in the context of fanfiction, it might be the work of a new, unknown group. This group could be after the knowledge Luke has about the Force. His kidnapping could be a way to force him to reveal secrets. The Jedi Order would be in chaos, and his students, if he has any at that point, would be left without their master. They might try to find him on their own, leading to their own character development and adventures.
It could be a new villain who has a soft spot for Bubbles. Maybe he's a misunderstood bad guy who just wants some attention. He might see Bubbles as a symbol of purity and kindness that he lacks in his life, so he kidnaps her in a rather desperate attempt to be close to her.
In such a fanfic, perhaps Bubbles would initially be terrified when kidnapped. But as time goes by, she might discover some kindness in her captor. Their relationship could develop gradually. For example, the captor might show her a different side of the world she never knew. And Bubbles, being the sweet and innocent one among the Powerpuff Girls, could start to have feelings for this person who is different from the usual villains she faces. This would create a complex dynamic where she has to balance her new - found feelings with her loyalty to her sisters and the city they protect.
One possibility is that Naruto's friends launch a rescue mission. They would use their unique skills, like Sasuke's Sharingan or Sakura's medical ninjutsu combined with her combat skills, to find and save Naruto.
Well, it could be a secret organization that has been operating in the shadows. They might have some ulterior motive related to Naruto's power or his connection to the Nine - Tails. Maybe they believe that by kidnapping Naruto, they can control the Nine - Tails and use it for their own purposes. Another option is a jealous ninja from within Konoha. This ninja might feel overshadowed by Naruto's achievements and popularity and decides to kidnap him to get him out of the picture. Also, a powerful and ancient being awakened from a long slumber could be the kidnapper. They see Naruto as a source of energy or a key to something they desire.
Well, in general, any form of fanfiction that involves kidnapping and bondage themes can be a bit dicey in terms of ethics. In the Naruto universe, which is mainly aimed at a younger audience in its original form, such themes are far from the original intention. However, in the realm of fanfiction for an older and more mature audience who understand the fictional and consensual nature of such works in that context, it could be seen as a creative exploration of different scenarios. But it's important to note that it should always stay within the boundaries of legality and respect for the original source material.
There could be a fanfiction where Naruto is kidnapped during a mission. In this case, the story could explore how his ninja skills and his strong will help him survive while captive. It might also show the internal struggle of the kidnappers, some of whom may start to question their actions after getting to know Naruto better.
In such a fanfiction, Naruto's friends would likely go on a desperate search for him. Sasuke might put aside his pride and team up with the others. They would follow any leads, like tracking the kidnapper's chakra signature if possible.